Restoration of correct βIVS2-654-globin mRNA splicing and HbA production by engineered U7 snRNA in β-thalassaemia/HbE erythroid cells

Sci Rep. 2019 May 21;9(1):7672. doi: 10.1038/s41598-019-43964-3.

Abstract

A cytosine to thymine mutation at nucleotide 654 of human β-globin intron 2 (βIVS2-654) is one of the most common mutations causing β-thalassaemia in Chinese and Southeast Asians. This mutation results in aberrant β-globin pre-mRNA splicing and prevents synthesis of β-globin protein. Splicing correction using synthetic splice-switching oligonucleotides (SSOs) has been shown to restore expression of the β-globin protein, but to maintain therapeutically relevant levels of β-globin it would require lifelong administration. Here, we demonstrate long-term splicing correction using U7 snRNA lentiviral vectors engineered to target several pre-mRNA splicing elements on the βIVS2-654-globin pre-mRNA such as cryptic 3' splice site, aberrant 5' splice site, cryptic branch point and an exonic splicing enhancer. A double-target engineered U7 snRNAs targeted to the cryptic branch point and an exonic splicing enhancer, U7.BP + 623, was the most effective in a model cell line, HeLa IVS2-654. Moreover, the therapeutic potential of the vector was demonstrated in erythroid progenitor cells derived from βIVS2-654-thalassaemia/HbE patients, which showed restoration of correctly spliced β-globin mRNA and led to haemoglobin A synthesis, and consequently improved thalassaemic erythroid cell pathology. These results demonstrate proof of concept of using the engineered U7 snRNA lentiviral vector for treatment of β-thalassaemia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Erythroid Precursor Cells / metabolism
  • Genetic Vectors / genetics
  • HeLa Cells
  • Hemoglobin E / genetics
  • Hemoglobin E / metabolism
  • Humans
  • Mice
  • RNA Splicing*
  • RNA, Small Nuclear / genetics*
  • RNA, Small Nuclear / metabolism
  • RNAi Therapeutics / methods*
  • beta-Globins / genetics*
  • beta-Globins / metabolism
  • beta-Thalassemia / genetics
  • beta-Thalassemia / therapy*

Substances

  • RNA, Small Nuclear
  • U7 small nuclear RNA
  • beta-Globins
  • Hemoglobin E